Telephone system



Jan. 9, 1940.

K. B'ALOU N TELEPHONE SYSTEM Filed April 14. 1938 INVENTOR. KURT BALOUN v BY Z Z ATTORNEY.

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Application April 14, 1938, Serial is. 201,915?

i In Germany April .19, 11937 p 3Claims. (01. 1 19 86),

.ments. I

This is achieved inthat during a selecting op .eration a plurality. of currents are connected to the .party line in' succession toconstitute the selecting current, the currentsfiowing either in the same direction over different leads or in different directionsover different leads or in difiersuccessively connected to diiferent leads or to the ,ent directions over the same leads.

The system can advantageously be so arranged that the selecting currents produced (for example by means of a magneto) at the sending statio-n are connected to the common line over a key set operated-at this station and a switch controlling thesuccession' of theselecting currentsin.

a manner characterizingthe wanted station. The switch possesses a number of contact positions corresponding tothe particular number of selecting curre'ntsto be transmitted and over these. positions the potentialsdetermined by the selecting key'contacts are connected to the party line. The control of the switch can take place automatically for example by a coupling which becomes efiective after a definite number of rotations of the selecting current generator. Y I Alternatively the switching can be made def pendent upon the calling subscriber in that the latter controls a separate switch or alternatively in that't-hesubscriber operates for example the selecting keys in a special way, for example, de-

presses them further and thus brings them into .another position.

a At the wanted station switching means which are responsivejto the direction of the current are same lead of the common line and connect up the calling device under the influence of the selecting currents which are applied in succession; A plurality of switching means responsive to the direction of the current are provided at each branch station; one of which is permanently connected to the common line while a. second switching means is connected to the common line when the first becomes operative, a third when the second becomesoperative and so on according to the number of selecting currents.

" the leads a, bu -of;the party line GL in different qwaysat the different branchstations, thusfor example in. the case o-f the first four subscribers TI- TA theArelays areconnectedto the a lead, ,while'in the case of subscribers T573118 they are case'o-f both these-subscribers, i; e.,fTl.l-T 8, only i one relay is associated with each lead of the party direction.

' Further details of the invention are set outin detailin the following description. Embodiments of. the invention are represented in the attached; drawing but the invention is not to be considered limited to these. 5"

F 1 shows the re g: devices Of'a branch station connected tea party line, one of which is adapted to be selected by two successive selecting currents; v Fig. 3 .the circuitoi the currentgenerator for the Q I Fig. 2.shows a sending device and selecting and ringing currents. In the twelve branch stations Tl.-Tl Zshown in Fig. 1, of which only thecalling devices with which the invention isfconcerned are showniinv detail, while the other devices can, be constructed in the known manner, 1'5

the calling devicesliateach station comprise two relays A, ,B .eachin, association with a rectifier,

and a 'bell,-LWK. The relays are associated with connected. to the. b-lead; Furthermore, in the line while in the case of the subscribers Til-T12 two relaysare connected to .one and the same lead. 'By means, of the rectifier Ga, Gb disposed in series with each relaylghflB) the relays can only be influenced by current in a particular a If now subscriber T4 for example-is to be called I a. current] impulse of negativedirection is first transmitted over thea-lead Consequently relay v. .A4 at the station Td energizes. In addition to i this relay the relaYSfA3. and All of the subscribers stations T3 and TI [are connected up. All three relays operate their. contacts (a). and

thereby connect the associated relays B3 and B4 and also BII to the b -lead in preparation. It i now following the first limpulse-a second impulse is transmitted this time in the positive direction over the b-lead, this, can operate on the relays I which have been connected up in preparation only in respect of the relays B3 and B4 connected to the b-lead. On account of the particular direction (positive) ofthe select ng impulse only relay B4 however and the bell WM at the station T4 are influenced. Relay B4 closes its contact 12 so that it is maintained operated as isgalso the bell WM throughout the duration of the second selecting impulse which also constitutes the ringing current. The relays A5; A6 and All! at the stations T5, T6 and Tl 0 which respondto this direc- 5 5 as fOllOWSZ tion of current are also energized by theringing current transmitted over the b-lead. False calls are not occasioned thereby since for these subscribers stations the ringing current flows in the other lead or in the other direction.

The selection of another subscriber for example subscriber T1: occurs in, a corresponding Way. In this case an impulse in the negative direction is first transmitted over the b-lead whereupon relay Al energizes and contacts relay B1 to the a-lead over its contact (a). The succeeding negative impulse over the a-lead switches on relay BI and the bell Wlc'l. I

If the subscriber TII is-wanted, ,animpulse in the negative direction is'first transmitted over the A-lead and this as has already been described causes relays A3, A l andAll toenergize.

The subsequent impulses in the positive: direction over the a-lead allows only relay Bil oi the preparatorily connected relays B3, B l and BH to operate. The bell Wlcil is operated at the same time as relay Bl I. The relays Al, A2 and A9 respond to the ringing current but do not cause the associated calling devices to operate.

Fig. 2 shows the arrangement .of-a key... set

-which-enables the individual subscribers to be selected. This key set can be provided either at the central station of the party line or at the subscribers stations. Its mode of' operation is If the key WT4 is operated in order to call subscriber T5 for example, negative potential is connected to the lead A and positive potential to the lead D. The negative potential connected to the lead A, since the switch U with its contacts at, it! are in the rest position, is immediately connected to the a-lead of the party line GL, while the potential connected to lead D.

is only connected to the party'line after the switching over of the switch U which takes place after a definite interval. "The mode of control of the switch is not shown in the embodiment. The switch can either be made as a manually operated switch and can be switched over by the calling subscriber after a certain time, or it can be coupled to the current generator, i. e., a magneto, in such a Way that after a definite number of rotations of the magneto shaft it is automatically brought into the rest or operated that station only.

alternating current can be taken and also direct current by a suitable arrangement of rectifiers. Earth can be connected to a metal tapping on the secondary side over a contact controlled by the selecting keys WTl-WTI 2. p In addition to the twelve subscribers stations shown :in the embodiment ,two further-subscribersstations cannabe called.selectivelynf calling devices are provided at these stations in bridge across the two leads of the party line, these -calling-devices only responding to direct current in a particular direction if this is transmitted over the double line.

If, the calling of; these two subscribers is not to be provided for, the transmission of ringing current alone over the double line can be used ior conference calls, for calling of the subscribers ,of'the: party line simultaneously. In this case aiurther ringing device bridged across the party line at each station is required. Therefore, by

operation of a-special conferencecall switch, which is ;not shown, here, alternating current is transmitted over the contacts rland 1"? over both leads of the party line. On this account. the conference calling devices are operated atall the branch stations.

What is claimed is: y 1. In a selecting system, a line having a pair of leads and having a plurality of stations .thereon, a pair of relays at eachstation connected to the leads thereof only through unidirectional devices, a signalling device at. eachstation also connected to a lead of the line only through a unidirectional device, sources .of current of differentpolarity, and means for successively connecting a pair oisaid sources'to the leads of the line tosuccessively operate the pair of relays associated with a particular station, and for then operating the signalling device associated with 2. In a selecting system, a line having a pair of leads and a plurality ofstations on the line, a first relay for each station normally connected I to the particular lead of the line, a second relay at each station'normally disconnected.- from the lineand connected to a particular'lead only by the operation of the first relay at that station, each of said relays responsive only, to a particular polarity and .means for successively connecting said sources to" the leads of said 'line=toselec- .tively signal only a particular-one of said stations.

3. In a telephonesystem, a party line having a pair of leads and a plurality of stations, sources of current of different polarity "and a sourceof ringing current, a pair of relays at each-station responsive to aparticular source, and means for successively applying either one of said sources to first one and thenanother of said leads or to one of said leads, or for successively applying one of said sources to one of-said leads or to first one and then another of saidleads to selectively signal a particular one of saidstations.

I KURT BALOUN. 

